Passkeys, multiple devices and having no biometric reader

Sorry, I still don't see how this any more secure than using a seriously secure master password in 1P. It seems to me that anyone who can figure out my 4-digit pin on my phone or Windows computer could then access all my 1P accounts with impunity. Using faceID or fingerprint biometrics just isn't far enough along as a technology. Sure, facial identification works great on TV or for the CIA but a tiny thing like wearing sunglasses completely baffles my Samsung phone. And a damp finger will never unlock anything where the original finger was dry. So, if my master password to 1P is 6Hvpq9#x.R4r (it's not), I change it every 3 months and all my other passwords are all different, random 20-character combinations, how are passkeys superior to this?